Hartmann's mountain zebra studbook 2011 - Marwell Zoo

More documents

Recommendations

Info

ecapture estimate is so high (74%) relative to the ‘source’ numbers. This suggests that the northern area of Gondwana Cañon Park is a key area for the wider population. Presumably, the reason for this is the fact that this area contains a reliable, abundant water supply plus a good food supply. The animals are generally in good condition, even in the late dry season, so do not appear to have reached carrying capacity, at least in years with average rainfall. The movements between FRCNP and GCP in the dry season must be driven by some, as yet unknown, relationship with the dry season water supply in the National Park, presumably the remaining pools in Fish River itself, and the relative availability of food there. NamibRand Nature Reserve (NRNR) We attempted a similar mark-recapture estimate in the northern part of the NRNR, an area of about 30,000 ha, using camera traps at 5 water holes. Unfortunately, equipment failures meant that cameras were not always operating simultaneously and so a simple analysis, pooling data from all the water holes, could not be used. Instead, I adopted an approach starting with separate estimates for the most commonly used water holes. The largest numbers were at Moringa water, the most north-easterly water source where mark and recapture periods of 48 hours each in October-November yielded an estimate of 158+/-12 mountain zebra. The next highest numbers, from slightly different sampling dates, were 87+/-13 and 77+/-17 at the two other main water holes. These estimates cannot be simply summed up because of overlap in use, so I quantified the overlap and corrected the numbers using the proportion of animals that occurred exclusively at each water hole during the sampling period. The adjusted values were then summed giving an estimate of 235 mountain zebra for these three key waterholes. A simple average of the standard errors for the three sites gave an estimate of 235+/-14. This value is higher than that from 2010 but the procedure was simpler in that year and is not strictly comparable. The 2011 value is based on 196 individuals actually identified at the three water holes, 83% of the estimate, and despite the methodological difficulties is probably quite realistic. The other two water holes sampled in the north-west of NRNR (one at Sossusvlei Desert Lodge) had fewer mountain zebra visiting and so a formal estimate could not be carried out. However, 24 individuals were identified over the last three months of the year, bringing the total for the northern area to about 259. There is a high level of connectivity between the two water holes in the north-east but none with the three main water holes sampled in the north-west. We believe that the mountain zebra living in the north-west are probably the southern edge of a sub-population that extends northwards beyond the boundaries of NamibRand and I am currently analysing the first results from camera trapping outside the northern boundary in a neighbouring property called Geluk. Although this work is at an early stage, 35 new animals have been found (and added to the ID library) and 5 animals (two in a breeding group and three bachelors) that had previously been seen inside NRNR have been identified. These are thus the first known individuals who definitely move in and out of the reserve. There were thus about 259 mountain zebra in the 30,000 ha northern part of NamibRand Nature Reserve (235 from the 3 north-eastern water holes plus 24 known at Sossusvlei Desert Lodge) giving a density of 0.86/km 2 . These were the numbers present in part of the Reserve out of a source population of over 424 (the numbers of individuals identified or otherwise known to have been present in 2011) and so represent about 61% of the wider population. From the point of view of population management this is good news for the reserve because the chance of a larger population remaining genetically viable is higher. However, it also means that the conservation of the wider population, in the Nubib mountains and beyond, is dependent on actions beyond the boundaries of the Reserve and thus on wider co-operation between landowners. AII
Hybridisation There have long been rumours of hybridisation between mountain zebra and plains zebra (Equus quagga burchellii) in Namibia and recent preliminary genetic analysis supports this possibility. My own interest started with observations of male mountain zebra becoming attached for long periods to particular breeding groups of plains zebra. This has been seen twice in NamibRand Nature Reserve and once on Gondwana Cañon Park, both areas where plains zebra have been re-introduced in recent times. In GCP the mountain zebra male was attached to one breeding group and rejoined it, even after mingling with other groups at water holes. He was subordinate to the plains zebra group stallion and this is also likely in the case of at least one male in NamibRand. This latter male was repeatedly injured, presumably in combat with a plains zebra male. No obvious hybrids have been seen in either area and these observations suggest that gene flow from male mountain zebra to female plains zebra may be unlikely because male plains zebra are larger and able to defend their females. Despite this, the observations show a remarkable behavioural attachment between individuals of the two species which raises the possibility of hybrid mating. A greater danger could arise when males compete for access to female mountain zebra because in this case the larger plains zebra stallions may win. In addition, there is regular ecological overlap. Mountain zebra and plains zebra have broadly distinct habitats but they often overlap. For example, in NamibRand plains zebra move up into the foothills of the Nubib mountains in the late dry season as the grassland of the plains are depleted. And in Gondwana in early 2012, mountain zebra were moving down onto the plains near Holoogberg as the wet season green flush appeared and, possibly, as the mountain zebra population expands. Where the two species overlap, they often occur at the same water holes. They never drink at the same time (in my experience) but may do so within a few minutes of each other and water holes are clearly places where these water-dependent species may start the process of forming social bonds. Of more immediate importance is the situation in Etosha National Park. Hybridisation has been reported there for some time and an earlier student (who unfortunately did not finish his studies) photographed animals that appear to be hybrids. I visited Etosha last October and spoke to a warden about the hybridisation issue. His view was that there were probably many hybrids in the western part of the park and that this may have come about because the normal western movements of mountain zebra into the mountainous areas to the west of the park may have been prevented when the boundary fence was erected. Hybrids reported elsewhere may also be partly due to restrictions of movement by fencing but this remains to be investigated. Clearly, there is an urgent need for targeted research into this problem with a view to designing appropriate management practices. Preliminary analysis of DNA collected in previous studies of zebra in Etosha reveal some evidence for hybridisation between the two species; for example one plains zebra had ~30% genetic assignment to mountain zebra (Pauline Kamath, pers comm.). Hopefully, a wider genetic study to test these findings and explore the causes will start soon and, using an individual-based approach, I will be helping to look at the behavioural and ecological basis of mate choice across the two species. There are many unknowns at the moment. Mountain zebra and plains zebra have clearly remained separate in evolutionary time so why is a problem occurring now? Or are the hybrids confined to a hybrid zone that will not affect the main populations? We cannot answer these questions at the moment but the possibility that confinement and fencing is creating a new and potentially dangerous situation should be tested. Hybridisation may be occurring in the west of Etosha NP because the fence at the western end of Etosha prevents natural movements by mountain zebra, and thus ecological separation from plains zebra. The risk of hybridisation may also occur elsewhere in Namibia when plains zebra are introduced into enclosed farms in mountain zebra habitat; or reintroduced into areas which previously contained plains zebra but where spatial dynamics have been altered by fencing. Thus, in spite of the fact that some mountain zebra populations are increasing in Namibia, a AII
Page 1 and 2: International International Studboo
Page 3 and 4: Contents Disclaimer AI Introduction
Page 5 and 6: Introduction Introduction The inter
Page 7 and 8: Hartmann’s Hartmann’s Hartmann
Page 9 and 10: Stripe tripe tripe project project
Page 11 and 12: Mountain zebra tracking The main co
Page 13 and 14: The movement data we are obtaining
Page 15 and 16: Logistical/operational and other su
Page 17: Gondwana Cañon Park (GCP) Backgrou
Page 21 and 22: The The Management anagement oof o
Page 23 and 24: Explanations Explanations The studb
Page 25 and 26: Age Age Age Pyramid Pyramid Pyramid
Page 27 and 28: Age Age Age Pyramid Pyramid Pyramid
Page 29 and 30: Institution nstitution nstitutions
Page 31 and 32: Germany Germany BERLIN TP EAZA, ISI
Page 33 and 34: Slovak Slovak Republic Republic BOJ
Page 35 and 36: HIGASHI M JAZA, ISIS Saitama Childr
Page 37 and 38: BUSCH TAM AZA Busch GardensTampa Ba
Page 39 and 40: Current Current Register Register o
Page 41 and 42: Status: Living on 25 May 2011 HARTM
Page 51 and 52: HARTMANN'S MOUNTAIN ZEBRA Studbook
Page 53 and 54: Deaths Deaths during during during
Page 57 and 58: Transfers Transfers during during 2
Page 61 and 62: Location Glossary - HARTMANN'S MOUN
Page 69 and 70:
Full Full Historical Historical Reg
Page 71 and 72:
HARTMANN'S MOUNTAIN ZEBRA Studbook
Page 73 and 74:
Page 75 and 76:
Page 77 and 78:
Page 79 and 80:
Page 81 and 82:
Page 83 and 84:
Page 85 and 86:
Page 87 and 88:
Page 89 and 90:
Page 91 and 92:
Page 93 and 94:
Page 95 and 96:
Page 97 and 98:
Page 99 and 100:
Page 101 and 102:
Page 103 and 104:
Page 105 and 106:
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Page 113 and 114:
Page 115 and 116:
Page 117 and 118:
Page 119 and 120:
Page 121 and 122:
Page 123 and 124:
Page 125 and 126:
Page 127 and 128:
Page 129 and 130:
Page 131 and 132:
Page 133 and 134:
Page 135 and 136:
Page 137 and 138:
Page 139 and 140:
Page 141 and 142:
Page 143 and 144:
Page 145 and 146:
Page 147 and 148:
Bibliography Bibliography Section S
Page 149 and 150:
Grobler, J. and A. Hall-Martin (198
Page 151 and 152:
Langenhorst, T. (2005): Internation
Page 153:
Shortridge, G. (1934): The mammals
show all

Hartmann's mountain zebra studbook 2011 - Marwell Zoo

Create successful ePaper yourself

Delete template?

Save as template?